Reduction of DNA mismatch repair protein expression in airway epithelial cells of premenopausal women chronically exposed to biomass smoke

Biomass burning is a major source of indoor air pollution in rural India. This study examined whether chronic inhalation of biomass smoke causes change in the DNA mismatch repair (MMR) pathway in the airway cells. For this, airway cells exfoliated in sputum were collected from 72 premenopausal nonsmoking rural women (median age 34 years) who cooked with biomass (wood, dung, crop residues) and 68 control women who cooked with cleaner fuel liquefied petroleum gas (LPG) for the past 5 years or more. The levels of particulate matters with diameters less than 10 and 2.5 μm (PM₁₀ and PM_2.5) in indoor air were measured by real-time aerosol monitor. Benzene exposure was monitored by measuring trans,trans-muconic acid (t,t-MA) in urine by high-performance liquid chromatography with ultraviolet detector. Generation of reactive oxygen species (ROS) and level of superoxide dismutase (SOD) in airway cells were measured by flow cytometry and spectrophotometry, respectively. Immunocytochemical assay revealed lower percentage of airway epithelial cells expressing MMR proteins mutL homolog 1 (MLH1) and mutS homolog 2 (MSH2) in biomass-using women compared to LPG-using controls. Women who cooked with biomass had 6.7 times higher level of urinary t,t-MA, twofold increase in ROS generation, and 31 % depletion of SOD. Indoor air of biomass-using households had three times more particulate matters than that of controls. ROS, urinary t,t-MA, and particulate pollution in biomass-using kitchen had negative correlation, while SOD showed positive correlation with MSH2 and MLH1 expression. It appears that chronic exposure to biomass smoke reduces MMR response in airway epithelial cells, and oxidative stress plays an important role in the process.     

California Statewide Assessment of the Effects of Ozone on Crop Productivity

Six properties appear desirable for any set of ozone attainment criteria: (1) sufficient stringency to protect public health, (2) simplicity and understandability, (3) sensitivity to real changes in air quality, (4) stability against meteorological fluctuations, (5) use of as much data as possible, and (6) equivalence between the stringency the criteria appear to mandate, and what they actually mandate. We consider how the federal attainment criteria might be improved with respect to Properties 4 through 6 while being equally strong on 1 through 3. Whether the federal standard meets Property 1 has been the subject of debate, but our analysis would apply also to a modified standard. We show that there are subtleties in how improvements might be made. In particular, basing the attainment status on a statistic with low variance may not lead to a more stable criterion, and although it is easy to find a criterion that makes it hard for a district with bad air to reach attainment, or a district with good air to get out of attainment, it is hard to find a criterion that does both. This suggests using different criteria for districts that are out of attainment from districts that are in attainment. Initially the burden of proof would be on the district to prove that its air is of attainment quality. However, once the district has achieved attainment the burden of proof would shift; the district would remain in attainment unless there was strong evidence to the contrary. An evaluation of a set of criteria based on this idea showed improvements over the federal criteria with respect to the last three desirable properties-stability, use of data, and equivalent stringency-with some sacrifice in simplicity and sensitivity.     

Changes in microbiological metabolism under chemical stress

Chemical stress may alter microbiological metabolism and this, in turn, may affect the natural and engineered systems where these organisms function. The impact of chemical stress on microbiological metabolism was investigated using model chemicals 2,4-dinitrophenol (DNP), pentachlorophenol (PCP), and N-ethylmaleimide (NEM). Biological activity of Pseudomonas aeruginosa was measured in batch systems, with and without stressors at sub-lethal concentrations. Stressor DNP, between 49 and 140 mg l(-1), and PCP, at 15 and 38 mg l(-1), caused decreases in biomass growth yields, but did not inhibit substrate utilization rates. These effects increased with stressor concentrations, showing as much as a 10% yield reduction at the highest DNP concentration. This suggests that a portion of carbon and energy resources are diverted from growth and used in stress management and protection. Stressor DNP, between 300 and 700 mg l(-1), and PCP at 85 mg l(-1) caused decreases in growth yields and substrate utilization rates. This suggests an inhibition of both anabolism and catabolism. Stressor NEM was the most potent, inhibiting biological activity at concentrations as low as 2.7 mg l(-1). These findings will ultimately be useful in better monitoring and management of biological treatment operations and contaminated natural systems.     

Analysis of marine sediment, water and biota for selected organic pollutants

The concentrations of various organic pollutants (benzo(a)pyrene (BaP), hexachlorobenzene (HCB) and pentachlorophenol (PCP)) were determined in samples of water, sediment and biota (flounder, killifish, shrimp, crabs and squid) from San Luis Pass, Texas. Sediment was also analyzed for polychlorinated biphenyls (PCBs), phthalic acid esters (PAEs) and various pesticides. Only PCP was detectable in water. In sediment, the relative concentrations were PAEs > BaP > (PCBs HCB) > PCP. In biota, BaP was not detectable in any animal; HCB was highest in crabs and PCP was highest in all others (flounder, killifish, shrimp and squid). The relative concentrations of HCB and PCP were different in the different organisms. The differences between the relative concentrations in the biota and in sediment are discussed. The results of this study are compared to values measured at other sites. This study is part of a larger effort to identify and quantitate pollutants in various Texas estuaries and to serve as a basis for monitoring marine pollution.     

Mineral reserves: Projected lifetimes and security of supply

This article analyses the lifetimes of reserves of three dozen important minerals. Despite the high rate of their extraction in the past 30 years, the recorded reserves of these non-renewable materials were higher in 1981 than in 1950 and they seem to meet foreseeable demand for a long time to come, as indicated by the estimated static lifetime for each of the minerals covered. The dynamic nature of ‘reserves’ is emphasized: further exploration and scientific and technological advance will add to the present proven reserves, and at a higher price further resources will be ‘upgraded’ into commercially exploitable reserves. Apparent long-term security can be disturbed by natural disasters, political events or other factors, especially in the case of minerals whose reserves and production are highly concentrated in one country. However, any such interruption in the continuity of supply is likely to be short-lived.     

Different patterns of growth and nitrogen uptake in two clones of marineSynechococcus spp.

We grew marineSynechococcus Clones WH7803 and WH8018 at 150µE m^–2 s^–1 in dilute batch cultures with NH ₄ ⁺ as the limiting nutrient. The maximal uptake capacities for NH ₄ ⁺ and NO ₃ ^- were measured in frequent experiments during log and stationary phases of growth. Clone WH7803, originally isolated from oceanic waters, had a specific uptake rate of NH ₄ ⁺ that approximated the maximum (log phase) specific growth rate (ca ~ 0.025 h^–1). NO ₃ ^- uptake was observed only after nitrogen in the media was depleted; the NO ₃ ^– uptake capacity was ca 12% the capacity for NH ₄ ⁺ uptake throughout the nitrogen depleted period. Growth was arrested upon nitrogen depletion, but resumed soon after reinoculation into fresh media, even after 5 d of starvation. Clone WH8018, originally isolated from coastal waters, revealed a five-fold enhancement in the NH ₄ ⁺ uptake rate relative to growth rate at the time of nitrogen depletion. As nitrogen starvation proceeded, this enhancement was reduced. This clone, too, was able to take up NO ₃ ^- once nitrogen in the media was depleted, but only after ca 20 h. Growth continued for a limited period during nitrogen depletion, but nitrogen-starved cells were slow to recover upon reinoculation into fresh media. We speculate that clonal differences may reflect differences in the molecular regulation of nitrogen assimilation.     

Evaluating a Canadian regional air quality model using ground-based observations in north-eastern Canada and United States

The simulated concentrations from a numerical 3-dimensional regional air quality model (MC2AQ) are compared to those of ground-based observations in north-eastern Canada and the United States. The model has oxidant chemistry for both inorganic and organic species and deposition routines driven online by a mesoscale compressible community meteorological model (MC2). A standard emission inventory of anthropogenic, natural and biogenic sources for the year 1990 for 21 atmospheric trace species was used in the simulation. The model was run for July 1999, because of the occurrence of a high ozone episode and the availability of the monitoring data for surface O3, SO2, NO, NO2 and NOx. The comparisons during the episode show that the model performs quite well for predicting concentrations and diurnal variations of the surface ozone. The predictions for other gaseous species show some discrepancies with observations, but they are consistent with the results from other models evaluated in the literature. The uncertainties in the emission inventory for these species might be the main causes of the discrepancies. Further studies are needed to improve the predictability of SO and NOx, especially as the model is developed to include particulate matter formation as a result of these gaseous precursors.